Any ideas on the Rumley problem he found

[racefastnow]

At the end of last year Runley wrote a letter thanking everyone for the great year and went on to talk about how he discovered an engineering flaw on the LR and designed something for about the same cost to reprint the rule book he added. I realize they now changed all the rules and barred half the stuff they were prolly doing but what are some thoughts about what's actually the engineering flaw he was talking about. Not really trying to get into the solution or whatever just was curious what people thought is actually wrong with the current design

[Aces&Eights]

4 bar sucks, its full of flaws. Today's cars are essentially an ensemble of crutches covering for each other. Its touted as being "Sophisticated" and "High Tech", but its just a collection of band aids attached to shiny billet aluminum trickery. Its too lengthy to get into on here but anyone who studies suspension or has an engineering background see most of the flaws right off. Essentially the whole modern setup package is done in an effort to deal with the outrageous action of the LR.

Its kind of like one of these new drugs you see advertised on TV, they cure or treat one problem but you get stuck with a dozen ugly side effects for your trouble. That's what today's 4 bar cars are, a back yard science project gone array with terrible side effects that require shock packages costing $$$ thousands to attempt to control the hyper suspension movements. But now that they've become popular the power elite are changing the rules so everyone has to play on the monkey bars. Innovation is all but dead and they saved us all a fortune too.

[Lizardracing]

The main advantage is the ability to ge the car to turn on the throttle through the middle.

What suspension would you use instead?

[Matt49]

We race in circles. So at the end of the day, it all boils down to having the perfect combination of rear-steer and balancing the loading of the rear tires in such a way that keeps us from spinning out. Sprinkle that in with controlling car attitude to maximize aero down force and you have the modern late model. Short of using an independent rear suspension, the 4-bar is about the best way to make it happen.
One of the many "crutches" that Aces is talking about would be LR travel limiting. The LR travel limiter is horribly disruptive to the balance of the car because of the weigh it rapidly unloads the LR. Without getting into details suffice to say that Rumley's device essentially fixed that problem and maintains a more desirable load on the LR tire while still achieving the goal of limiting travel.

[keeks]

I find it amusing in a way that the 4 bar is full of flaws, and the engineer sees it for what it is, but at the same time late models have never been faster.

What rear suspension should we all be using if this is the case?

[MasterSbilt_Racer]

I find it amusing in a way that the 4 bar is full of flaws, and the engineer sees it for what it is, but at the same time late models have never been faster.

What rear suspension should we all be using if this is the case?

It would be something that can't be done now. But, there is no final answer, things move forward if the rules allow.

[keeks]

I agree MBR

[48bad]

I agree with aces&eights on this one.

[Kromulous]

Rumley's main focus was on, IMHO, the fact the LR travel makes traction, but the fwd movement, or rear steer takes it away. So there is the rub, more hike, more rear steer, one fights the other. That device allowed them to stay hiked up, and when on the gas would take out rear steer.

[Matt49]

Rumley's main focus was on, IMHO, the fact the LR travel makes traction, but the fwd movement, or rear steer takes it away. So there is the rub, more hike, more rear steer, one fights the other. That device allowed them to stay hiked up, and when on the gas would take out rear steer.

A spring rod for a RR upper bar used to accomplish the same thing :-)

[MasterSbilt_Racer]

A spring rod for a RR upper bar used to accomplish the same thing :-)

If you make things look really complex, people don't figure it out. lol

[racefastnow]

i was thinking it was the opposite, where on the gas it had the roll steer, but under braking it would pull the roll steer back out of it without unloading the RF,RR. not the case?? it was the opposite.

[Kromulous]

Actually i think your correct, i had it backwards, still got the pics. Cool device LOL.

Spring rods too, cool.

[Krooser]

When we ran buggy springs we had full fields, packed grandstands and $1000 cars that ran for $500 features. Seems we've gone backwards...

[MBR Performance]

Anybody have one of those spring rods for sale?

[MasterSbilt_Racer]

Anybody have one of those spring rods for sale?

I got one of the ones from the 90s.

[a25rjr]

I got one of the ones from the 90s.

Afco or Penske?

[RacerX10]

Can we still run those spring rods ? I've got one laying around (AFCO).

[MasterSbilt_Racer]

Afco. Not legal if your sanction adopted the unified rules.

[let-r-eat]

Instead of which spring has the weight it would then be which BAR has the weight?

[CCHIEF]

Anybody have one of those spring rods for sale? http://shop.penskeshocks.com/PS-HTD-Spring-Bar/ . http://www.speedwaymotors.com/Tech/Ultimate-Spring-Rod-Guide.html

[MBR Performance]

The AFCO is no longer made and the Penske is way over priced. I'd rather by used for testing purposes.

[King1]

Bicknell still makes the standard ones like the old afco's for a reasonable price. They also make the precision control link which is like the Penske spring rod, but bicknell tells me that Penske buys most of their parts from them to manufacture their unit. They also told me that their sales to DLM teams went up last season lol.

[a25rjr]

LOL....Since our team was sponsored by Penske shocks in 1997, we were one of the first dirt teams to use one. Penske called them "hydraulic tracking dampner". I guess that's too fancy of a name for dirt cars.

[ALF401]

How much travel do the spring rods have?

[MasterSbilt_Racer]

How much travel do the spring rods have?

You could get about an inch out of the AFCO, if sprung light enough to allow it.

[RacerX10]

You could get about an inch out of the AFCO, if sprung light enough to allow it.

Curious .. I guess it's not legal now, but how come I never saw anybody running those recently ?

[MasterSbilt_Racer]

Curious .. I guess it's not legal now, but how come I never saw anybody running those recently ?

I think the Penske is really the only one people were running recently. I always thought they were too much of a hero or zero deal.